Supported gold catalysis: from small molecule activation to green chemical synthesis

Preparation and use of DMF-stabilized iridium nanoclusters as methylation catalysts using methanol as the C1 source

We report methylations of alcohols and anilines catalyzed by DMF-stabilized Ir nanoclusters using methanol as the C1 source. The DMF-stabilized Ir nanoclusters were prepared in one step and have diameters of 1-1.5 nm. They react in a borrowing-hydrogen reaction and are efficient methylation catalysts (TON up to 310 000).

A highly active worm-like PtMo nanowire for the selective synthesis of dibenzylamines

Worm-like nanowires are among the most active nanomaterials. In this study, we report the synthesis of dibenzylamine (DBA) motifs from reductive amination of either aldehydes or nitriles catalyzed by entirely new worm-like PtMo nanowires (PtMo WNWs). Under the assistance of H₂ gas, PtMo WNWs can be prepared in a facile manner, following which, their structure and composition are characterized by TEM, XRD, XPS, etc. Upon careful optimization of reaction parameters, the as-prepared PtMo WNWs work effectively in the activation of dihydrogen molecules, and both aldehydes and nitriles can be used as starting materials to fabricate DBAs under mild and green conditions. The reaction kinetics has been investigated, which reveals that the PtMo WNWs show superior activity in the conversion of imines into amines. This study provides a practical advancement in the preparation of amines. Moreover, the protocol reported herein is feasible for the synthesis of worm-like nanostructures with designed composition for various catalytic applications.

An efficient synthetic pathway of dibenzylamine (DBA) motifs from reductive amination of either aldehydes or nitriles catalyzed by highly active worm-like PtMo nanowires.

Diverse modes of functionalisation of ruthenium coordinated β-ketoiminate analogues

Varying chelation assisted as well as solvent dependent reactivity profiles of isostructural β-ketoiminate analogues explicate their non-spectator behaviour and fractional redox non-innocence.

Organic solvent extraction-assisted catalytic hydrothermal liquefaction of algae to bio-oil

MgSO₄-assisted ethanol extraction combined with catalytic hydrothermal liquefaction of algae to bio-oil.

Correlation between hydrogen yield and product distribution in algae conversion through an isopropanol/water system

Catalytic liquefaction of algae to bio-oil through an isopropanol/water system and correlation between hydrogen selectivity and product distribution.

Synthesis of Formate Esters and Formamides Using an Au/TiO₂-Catalyzed Aerobic Oxidative Coupling of Paraformaldehyde

A simple method for the synthesis of formate esters and formamides is presented based on the Au/TiO₂-catalyzed aerobic oxidative coupling between alcohols or amines and formaldehyde. The suitable form of formaldehyde is paraformaldehyde, as cyclic trimeric 1,3,5-trioxane is inactive. The reaction proceeds via the formation of an intermediate hemiacetal or hemiaminal, respectively, followed by the Au nanoparticle-catalyzed aerobic oxidation of the intermediate. Typically, the oxidative coupling between formaldehyde (2 equiv) and amines occurs quantitatively at room temperature within 4 h, and there is no need to add a base as in analogous coupling reactions. The oxidative coupling between formaldehyde (typically 3 equiv) and alcohols is unprecedented and occurs more slowly, yet in good to excellent yields and selectivity. Minor side-products (2-12%) from the acetalization of formaldehyde by the alcohol are also formed. The catalyst is recyclable and can be reused after a simple filtration in five consecutive runs with a small loss of activity.

The development of novel Au/CaO nanoribbons from bifunctional building block for biodiesel production

Herein, a novel and facile high-yield strategy is reported to efficiently fabricate 1D self-supported Au/CaO nanocatalysts using dual metal co-ordination polymers as templates. Significantly, a uniform distribution of dual metal nanoparticles can be ensured due to the fact that both Ca²⁺ and Au³⁺ ions are initially introduced into the co-ordination polymer via chemical bonding with bifunctional organic linkers and then, the Au and CaO nanoparticles are formed simultaneously in one pot via calcination. Furthermore, the as-prepared Au/CaO nanoribbons exhibit excellent catalytic performance in the transesterification reaction, which can be attributed to the small size and high distribution of CaO nanoparticles as well as the special 1D structure with high surface area. Moreover, leaching and deactivation, which are the main problems of CaO-based catalysts, are remarkably reduced due to the presence of hydrophobic Au nanoparticles on the surface of the CaO nanoribbons. Consequently, the Au/CaO nanoribbons can be used as recyclable catalysts with high activity for biodiesel production.

Gold-Triggered Uncaging Chemistry in Living Systems

Recent advances in bioorthogonal catalysis are increasing the capacity of researchers to manipulate the fate of molecules in complex biological systems. A bioorthogonal uncaging strategy is presented, which is triggered by heterogeneous gold catalysis and facilitates the activation of a structurally diverse range of therapeutics in cancer cell culture. Furthermore, this solid-supported catalytic system enabled locally controlled release of a fluorescent dye into the brain of a zebrafish for the first time, offering a novel way to modulate the activity of bioorthogonal reagents in the most fragile and complex organs.

Recent progress on single-molecule nanocatalysis based on single-molecule fluorescence microscopy

Understanding the heterogeneous catalytic properties of nanoparticles is of great significance for the development of high efficient nanocatalysts, but the intrinsic heterogeneities of nanocatalysts were always covered in traditional ensemble studies. This issue can be overcome if one can follow the catalysis of individual nanoparticles in real time. This paper mainly summarizes recent developments in single-molecule nanocatalysis at single particle level in Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. These developments include the revealing of catalytic kinetics of different types (plane & edge) of surface atoms on individual Pd nanocubes, the observing of in situ deactivation of individual carbon-supported Pt nanoparticles during the electrocatalytic hydrogen-oxidation reaction, and the measurement of catalytic activation energies on single nanocatalysts for both product formation process and dissociation process, etc. These studies further indicate the advantages or unique abilities of single-molecule methods in the studies of nanocatalysis or even chemical reactions.

Monodispersed gold nanoparticles supported on a zirconium-based porous metal–organic framework and their high catalytic ability for the reverse water–gas shift reaction

A highly active and selective Au@UIO-67 catalyst has been assembled.

Surface chemistry of group IB metals and related oxides

Catalytic surface chemistry of IB metals are reviewed with an attempt to bridge model catalysts and powder catalysts.

Surface Coating by Gold Nanoparticles on Functional Polymers: On-Demand Portable Catalysts for Suzuki Reactions

We have developed new functionalized polymers capable of being easily coated by gold nanoparticles, uniformly distributed on the surface of the polymers, by simply adding a gold(III) solution in water to the polymers. The polymer-supported gold nanoparticle material was used as an efficient portable and reusable catalyst for Suzuki reactions in mixed organic-aqueous solvents.

Harnessing the Power of the Water-Gas Shift Reaction for Organic Synthesis

Since its original discovery over a century ago, the water-gas shift reaction (WGSR) has played a crucial role in industrial chemistry, providing a source of H2 to feed fundamental industrial transformations such as the Haber-Bosch synthesis of ammonia. Although the production of hydrogen remains nowadays the major application of the WGSR, the advent of homogeneous catalysis in the 1970s marked the beginning of a synergy between WGSR and organic chemistry. Thus, the reducing power provided by the CO/H2 O couple has been exploited in the synthesis of fine chemicals; not only hydrogenation-type reactions, but also catalytic processes that require a reductive step for the turnover of the catalytic cycle. Despite the potential and unique features of the WGSR, its applications in organic synthesis remain largely underdeveloped. The topic will be critically reviewed herein, with the expectation that an increased awareness may stimulate new, creative work in the area.

Industrial Applications of Gold Catalysis

Gold catalysis has recently found its first large-scale applications in the chemical industry. This Minireview provides a critical analysis of the success factors and of the main obstacles that had to be overcome on the long way from the discovery to the commercialization of gold catalysts. The insights should be useful to researchers in both academia and industry working on the development of tomorrow's gold catalysts to tackle significant environmental and economic issues.

Gold on Different Manganese Oxides: Ultra-Low-Temperature CO Oxidation over Colloidal Gold Supported on Bulk-MnO2 Nanomaterials

Nanoscopic gold particles have gained very high interest because of their promising catalytic activity for various chemicals reactions. Among these reactions, low-temperature CO oxidation is the most extensively studied one due to its practical relevance in environmental applications and the fundamental problems associated with its very high activity at low temperatures. Gold nanoparticles supported on manganese oxide belong to the most active gold catalysts for CO oxidation. Among a variety of manganese oxides, Mn2O3 is considered to be the most favorable support for gold nanoparticles with respect to catalytic activity. Gold on MnO2 has been shown to be significantly less active than gold on Mn2O3 in previous work. In contrast to these previous studies, in a comprehensive study of gold nanoparticles on different manganese oxides, we developed a gold catalyst on MnO2 nanostructures with extremely high activity. Nanosized gold particles (2-3 nm) were supported on α-MnO2 nanowires and mesoporous β-MnO2 nanowire arrays. The materials were extremely active at very low temperature (-80 °C) and also highly stable at 25 °C (70 h) under normal conditions for CO oxidation. The specific reaction rate of 2.8 molCO·h(-1)·gAu(-1) at a temperature as low as -85 °C is almost 30 times higher than that of the most active Au/Mn2O3 catalyst.

Au@Cu(II)-MOF: Highly Efficient Bifunctional Heterogeneous Catalyst for Successive Oxidation-Condensation Reactions

A new composite Au@Cu(II)-MOF catalyst has been synthesized via solution impregnation and full characterized by HRTEM, SEM-EDS, XRD, gas adsorption-desorption, XPS, and ICP analysis. It has been shown here that the Cu(II)-framework can be a useful platform to stabilize and support gold nanoparticles (Au NPs). The obtained Au@Cu(II)-MOF exhibits a bifunctional catalytic behavior and is able to promote selective aerobic benzyl alcohol oxidation-Knoevenagel condensation in a stepwise way.

Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation

The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm(-3)) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability.

Silica-supported ultra small gold nanoparticles as nanoreactors for the etherification of silanes

Ultra-small Au–SiO₂ nanoparticles worked as nanoreactors for the etherification of silanes with high selectivity and reusability.

In situ formation of gold nanoparticles on magnetic halloysite nanotubes via polydopamine chemistry for highly effective and recyclable catalysis

A simple and green approach to fabricate magnetic halloysite nanotubes supported Au nanoparticles composite from bio-inspired polydopamine chemistry was demonstrated for highly effective and recyclable catalysis.

Cu–Ag/hydrotalcite catalysts for dehydrogenative cross-coupling of primary and secondary benzylic alcohols

The development of new and inexpensive heterogeneous catalysts for direct C–C cross-coupling of primary and secondary alcohols is a challenging goal and has great importance in academic and industrial sectors.